class Solution {
    vector<vector<int>> ret;
    vector<int> path;
public:
    vector<vector<int>> subsets(vector<int>& nums) {
        dfs(nums,0);
        return ret;
    }
    void dfs(vector<int>& nums,int i)
    {
        if(i==nums.size())
        {
            ret.push_back(path);
            return;
        }

        dfs(nums,i+1);

        path.push_back(nums[i]);
        dfs(nums,i+1);
        path.pop_back();
    }
};
